The current method used for constructing concrete slab floors is to initially set into the ground a plurality of wooden stakes around the outer periphery of the unpoured slab. A reusable wood form is next attached to the stakes by means of nails or screws. To the inside surface of the form is placed an insulation barrier that is attached to the forms by means of an adhesive and/or special nails. After the composite form is securely in place, the concrete slab is poured.
Once the concrete slab has set and hardened, the wood form is manually removed from the insulation barrier and the stakes. The exposed insulation barrier is then covered with a metal sheath that is placed over the top of the barrier.
A search of the prior art did not disclose any patents that directly read on the claims of the instant invention. However, the following U.S. patents were considered related:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,340,200 Stegmeier 20 July 1982 4,141,532 Wall 27 February 1979 4,027,846 Caplat 7 June 1977 3,016,225 Hughes 9 January 1962 ______________________________________
The Stegmeier patent approaches the problem of holding a form board in place to a support stake with a U-shaped spring clip. This clip contains fingers to grasp the top and bottom edge of the form while applying pressure to a round stake. The clip is in two separate pieces one to attach to the board and the other to apply spring pressure to the stake.
The Wall patent discloses an extruded U-shape frame that is cast integral with the edge of a flat concrete building panel and becomes the edge molding for attachment to a wall. Connecting means are incorporated into this molding with corner frame members completing the structure.
The Caplat patent utilizes a panel for casting concrete walls. The panel has steel sheets on the front and rear and rigid polyurethane foam cast in situ between the panel walls. The utility lies in weight and self-heating of the concrete in that the low thermal conductivity permits the heat generated in curing to be retained permitting a rapid setting of the concrete. The panel is removed when the concrete is set.
The Hughes patent discloses an attaching lever to retain a form and lock it into place with an over center cam-lock lever compressibly holding a hollow stake. A support channel contains top and bottom flanges that retain the wooden form and the attaching lever.
For background purposes and as indicative of the art to which the invention relates, reference may be made to the following U.S. patents:
______________________________________ U.S. PAT. NO. INVENTOR ISSUED ______________________________________ 4,022,437 French 10 May 1977 3,595,515 Rollow 27 July 1971 2,741,821 Findley 17 April 1956 ______________________________________